What is Medicare Part B?

by David Bynon, last updated

Medicare Part B is medical coverage for people with Original Medicare benefits. It covers doctor visits, preventative care, tests, durable medical equipment, and supplies. Medicare Part B pays 80 percent of most medically necessary healthcare services.

Key Takeaways

  • Medicare Part B covers outpatient medical services.
  • Medicare Part B has a monthly premium and an annual deductible.
  • After the annual deductible is met, Medicare pays 80 percent of all covered services.
  • Assistance programs and supplemental insurances can help with the remaining 20 percent of Part B costs.
  • Beneficiaries can enroll in Medicare Part B during their Initial Enrollment Period or the General Enrollment Period.
  • For most beneficiaries, the monthly Part B premium is deducted from their Social Security or Railroad Retirement Board benefits.
  • Medicare Part B coverage will be terminated if its monthly premium has not been paid.

What Does Medicare Part B Cover?

Medicare Part B covers preventative care services and most medically necessary outpatient services. Preventative care services, such as vaccines and screenings, help prevent or detect illnesses early on.  Medically necessary health services include the health services and supplies needed to diagnose and treat medical conditions.1Medicare.gov, “What Part B covers“, Accessed October 21, 2021

What Does Medicare Part B Not Cover?

Medicare Part B does not cover many common medical services and supplies deemed medically unnecessary. This includes routine dental care, vision care, hearing care, and cosmetic surgery. Part B does not cover inpatient care services that are covered by Medicare Part A.2Medicare.gov, “What’s not covered by Part A & Part B?“, Accessed October 21, 2021

Does Part B Cover Prescription Drugs?

Medicare Part B provides limited coverage for outpatient prescription drugs, but only under certain conditions. Drugs covered by Part B are usually medication given at a doctor’s office that wouldn’t be self-administered:3Medicare.gov, “Prescription drugs (outpatient)“, Accessed October 21, 2021

  • Drugs used with an item of durable medical equipment (DME)
  • Some antigens
  • Injectable osteoporosis drugs
  • Erythropoiesis-stimulating agents
  • Blood clotting factors
  • Injectable and infused drugs
  • Oral End-Stage Renal Disease (ESRD) drugs
  • Parenteral and enteral nutrition (intravenous and tube feeding)
  • Intravenous Immune Globulin (IVIG) provided in the home
  • Flu shots, pneumococcal shots, Hepatitis B shots (vaccinations)
  • Transplant / immunosuppressive drugs

Other prescription drugs beyond this list are covered by Medicare Part D plans. Drugs covered by Part D are usually self-administered or administered by a pharmacist.4Medicare.gov, “Prescription drugs (outpatient)“, Accessed October 21, 2021.

How Much Does Part B Cost?

Medicare Part B coverage has three costs:

  • Monthly Premium
  • Annual Deductible
  • Coinsurance

The Part B premium ($158.50 in 2022) must be paid each month to benefit from Part B coverage. There are a few services covered at no cost, such as the annual wellness visit, however, most Medicare-approved healthcare services have an out-of-pocket cost.5Medicare.gov, “Medicare costs at a glance“, Accessed October 21, 2021

The first out-of-pocket cost is the annual deductible ($203 in 2021). Beneficiaries pay the Part B deductible before Medicare starts paying its share. After the annual Part B deductible is paid, beneficiaries pay a 20 percent coinsurance for each Medicare-approved service.5Medicare.gov, “Medicare costs at a glance“, Accessed October 21, 2021

Part B Late Enrollment Penalty

If a beneficiary does not enroll in Part B when they are first eligible, they will have to pay a late enrollment penalty. A beneficiary’s Part B premium will increase by ten percent for every twelve-month period they were eligible for Part B but were not enrolled unless they had other creditable coverage.6Medicare.gov, “Part B late enrollment penalty“, Accessed October 21, 2021

How To Get Help Paying For Part B

Financial aid is available through Medicaid and the Medicare Savings Program (MSP). Medicaid assists low-income families and individuals. Certain low-income Medicare beneficiaries can also qualify for Medicaid and receive dual-eligible healthcare benefits. Medicare is the primary payer and Medicaid assists with premiums and out-of-pocket costs.7Medicare.gov, “Medicaid“, Accessed October 25, 2021

Qualifying Medicare beneficiaries that do not qualify for full Medicaid may qualify for premium and copayment assistance through the Medicare Savings Program. The level of MSP assistance is based on a beneficiary’s income.  Three of the four MSPs assist with Part B costs:8Medicare.gov, “Medicare Savings Programs“, Accessed October 21, 2021

  • Qualified Medicare Beneficiary (QMB)
  • Specified Low-Income Medicare Beneficiary (SLMB)
  • Qualifying Individual (QI)

Additional Insurance

Medicare supplement insurance (Medigap) is another tool beneficiaries can use to assist with Medicare Part B costs. All current Medigap plans (A, B, C, D, F, G, K, L, M, and N) cover some or all of a Medicare beneficiary’s Part B coinsurance. A few cover Part B Excess Charges, as well. Medicare Supplement  Plan C and Plan F cover the Part B deductible, however, these plans are no longer available to people who qualified for Medicare on or after 1 January 2020.9Medicare.gov, “How to compare Medigap policies“, Accessed October 21, 2021

When To Enroll In Part B

Most people qualify to enroll in Medicare Part B during their Initial Enrollment Period at age 65. People qualified for Social Security Disability Insurance (SSDI) because of certain disabilities are automatically enrolled in Medicare Part A and Part B on their 25th month of SSDI payments.10CMS.gov, “Top 5 things you need to know about Medicare Enrollment”, Accessed September 21, 2021

Is Medicare Part B Mandatory?

Medicare Part B is optional. It is not mandatory to enroll in Medicare Part B at age 65 or when receiving Social Security disability benefits. However, it appears mandatory due to the potential penalties if not enrolled.

When a beneficiary has creditable health coverage through an employer or union they can delay enrollment until they no longer have coverage. Beneficiaries with creditable coverage that have decided to delay Part B enrollment receive a two months Special Enrollment Period to make Medicare enrollment elections once their creditable coverage has ended.11Medicare.gov, “Special circumstances (Special Enrollment Periods)“, Accessed October 25, 2021

Getting Part B Assistance?

For questions about their Medicare Part B coverage and costs, beneficiaries can speak with a Medicare professional at 1-800-MEDICARE (1-800-633-4227). TTY: 1-877-486-2048.12Medicare.gov, “Pay Part A & Part B premiums“, Accessed October 20, 2021


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